Pyrimidine derivatives and process for preparing the same

ABSTRACT

Pyrimidine derivatives represented by the formula,   wherein R1 and R2 are individually a hydrogen atom or a methyl group, and R3 is a group formed by removing the carboxyl group from a carboxylic acid, are quite useful in acylating compounds having amino and/or imino and/or hydroxyl groups. The pyrimidine derivatives can easily be prepared by reacting a 2-mercapto-4and/or 6-methyl-substituted or unsubstituted pyrimidine with a carboxylic acid or a reactive derivative thereof in an inert solvent.

United States Patent 11 1 Nagasawa et al.

11] 3,904,612 Sept. 9, 1975 PYRIMIDINE DERIVATIVES AND PROCESS FOR PREPARING THE SAME [75] Inventors: Takeshi Nagasawa; Katumasa Kuroiwa; Kouichi Narita, all of Koriyama, Japan 73 Assignee: Nitto Boseki Co., 1.111., Fukushima,

Japan 22 Filed: Sept. 20, 1972 211 App]. No.: 290,575

[30] Foreign Application Priority Data July 22, 1971 Japan 46-74041 Sept. 23, 1971 Japan 46-74237 Oct. 19, 1971 Japan 46-82663 [52] US. CL... 260/240 J; 260/1125 R; 260/251 R;

' 260/2565 R; 260/691 [51] Int. Cl C07d 51/40 [58] Field of Search 260/240 .1, 251 R, 256.5 R

[56] References Cited UNITED STATES PATENTS 3,565,894 2/1971 DAmico 260/247.l

OTHER PUBLICATIONS Bardos et al., Tetrahedron Letters No. 16, pp. 1759 to 1764 (1966). Pratt et al., Biochemistry Vol. 10, No. 17, pp. 3178 to 3185 (1971). Lowy, An Introduction to Organic Chemistry, 6th Ed.,

p. 213, John Wiley and Sons (NY) (1945).

Lloyd et al., J. Chem. Soc. 1971 Part C, pp. 2890 to 2896.

DAmico et al., Rubber Chemistry and Technology, Vol. 41, pp. 704 to 720 (1968).

Dutta et al., .1. Chem. Soc. 1971, Part C, pp. 2896 to 2902.

Dixon et al., .1. Chem. Soc. Vol. 91, p. 124 (1907).

Primary Examiner-John D. Randolph Attorney, Agent, or Firm-Karl W. Flocks [57] ABSTRACT Pyrimidine derivatives represented by the formula,

20 Claims, 16 Drawing Figures PAIENIED 9I975 3,904,612

SHEET 1 111 g 100 FIG I Z S80 W 'I/V// ..\/\V/ 1 v 1 U) 5 00 w u Q 0 1E 4000 2000 1500 1000 500 200 WAVE NUMBER (cm") FIG 2 TRANSMISSION N b o o o FIG.3

WAVE NUMBER (cm") /o TRANSMISSION WAVE NUMBER (cm") FIG. 4

0 4000 2000 I500 1000 500 200 WAVE NUMBER (cm") "/0 TRANSMISSION I PAIENIEDSEP 91975 3,904,612

smear 3 l TRANSMISSION FIG. 6

WAVE NUMBER (crh") moo lu TRANSMISSION FIG 7 WAVE NUMBER'(cm') /0 TRANSMISSION- N J-\ m o o o FIG.8

I000 500 200 WAVE NUMBER (cm") /0 TRANSMISSION WAVE NUMBER ((Im") PAIENIEDSEP 9I975 3,904,612

SHEET 3 0f 1 2 FIG. 9

WAVE NUMBER (cm") FIG. I

WAVE NUMBER (cm") 2 FIG. I I

WAVE NUMBER (cm') FIG. I2

WAVE NUMBER (cm") PATENTEDSEP 9:915

/o TRANSMISSION /o TRANSMISSION /o TRANSMISSION g 8 8 8 g 8 sum u o g FIG.I3

WAVE NUMBER (x10' crfi') WAVE NUMBER (cm' 1 9 18 1 7 1 6 1 5 1 4 1 3 WAVE NUMBER (MO cm") FIG. l6 3 Mr/w A rm 6O l 111/ I 40 1/1 WAVE NUMBER (cm") PYRIMIDINE DERIVATIVES AND PROCESS FOR PREPARING THE SAME This invention relates to novel pyrimidine derivatives, a process for producing the same and a method for using thereof in acylating amines, hydrazines, alcohols and phenols.

As is well known, peptides are extremely useful compounds for foods and pharmaceuticals or for synthesis of other compounds. A number of peptides have been synthesized and studied heretofore. In the synthesis of peptides there have been used various active esters. The peptide bond, for example, is formed by reacting a N-protected amino acid or N-protected peptide having a free or active carboxyl group with a carboxylprotected amino acid or carboxyl-protected peptide having a free or active amino group.

in repeated reactions of peptide synthesis, yield is a very important factor. In case the reactions of optically active materials, it is important to maintain the optical activities ofthe materials without causing racemization during the reactions. Further, it is necessary that aftertreatment is easy and pure products can be obtained without causing any side reactions after completion of the reactions.

In order to meetthe conditions mentioned above, there have been proposed many carboxylic acid derivativcs as active esters. Among these carboxylic acid derivatives, acyl azides are known to have excellent effect on inhibiting racemization. However, the acyl azides have such disadvantages as not only decreasing the yield and easily taking place side reactions but also necessitating much care in storing and handling them and in conducting the reaction under severely controlled conditions since they are unstable.

Other active esters heretofore been proposed have suchdrawbacks as having selectivity in reaction, that is, they react with only specific amino acids or peptides, resulting in difficulty in purifying the obtained peptides. and the like. Further, there are other drawbacks in the known processes; for example. in acylating various amines, phenols or alcohols wherein they have hydroxyl group together with amino and/or imino groups, when selective acylation of only the amino and/or imino groups is required, as is particularly important in acylating biochemically important saccharides, steroids and the like, the, known active esters react not only with the amino and/or imino groups but also with the hydroxyl group, so that the hydroxyl group other than the amino and/or imino groups to be acylated would have previously been protected by other protective groups.

With an aim to overcome the various drawbacks of the known active esters, the present inventors made extensive studies with respect to the functions and production processes of pyrimidine derivatives to find that the special pyrimidine derivatives are suitable for various useful applications and have markedly excellent functions as acylating agents for acylating amines, hydrazincs, alcohols and phenols, above all as active esters in peptide syntheses, and that the pyrimidine derivatives can easily be produced on commercial scale. Based on the above finding, the inventors have accomplished the present invention.

The term acylation includes the formation of amide bond, imide bond, ester bond or peptide bond by reacting said pyrimidine derivatives with amines, im-

2- ines, hydrazines, alcohols, phenols, N-terminal free amino acids or N-terminal free peptides,

The above-mentioned pyrimidine derivatives are novel compounds and processes for acylating amines, hydrazines, alcohols and phenols by use of such novel compounds have not been proposed yet.

An object of the present invention is to provide novel pyrimidine derivatives.

Another object of the present invention is to provide a process for producing the novel pyrimidine derivatives.

A further object of the present invention is to provide a method for using said pyrimidine derivatives as acylating agent or active ester in acylating amines, hydrazines, alcohols and phenols or in peptide syntheses.

Other objects and advantages of the present invention will become apparent from the description made hereinbelow.

The novel pyrimidine derivatives of the present invention are represented by the formula,

wherein R and R are individually a hydrogen atom or a methyl group; and R is a group formed by removing the carboxyl group from a carboxylic acid.

The group formed by removing the carboxyl group from a carboxylic acid, represented by R in the formula (l), includes those formed by removing the car boxy] group from carboxylic acids such as straight chain or branched chain saturated or unsaturated aliphatic carboxylic acids having I to 20 carbon atoms, aromatic carboxylic acids which may contain hetero atoms such as N, S and O, aralkyl carboxylic acids and amino acids wherein the functional groups such as amino group are properly protected. These carboxylic acids mentioned above may contain further various substituents and protected functional groups. Thus R includes, for example, an aliphatic radical such as a straight chain or branched chain alkyl group having 1-20 carbon atoms, an alkenyl group having l-2O car bon atoms, an alkynyl group having l-20 carbon atoms, an alkoxyalkyl group, a haloor polyhaloalkyl group; an alicyclic group; an aromatic radical such as a phenyl group, a substituted phenyl group, a tolyl group, a naphthyl group, anthracene; a heteroeyc lic radical such as a pyridyl group, a furyl group; an aralkyl radical; an protected or non-protected aliphatic amino radical.

The pyrimidine derivatives represented by the formula (I) include, for example, the following compounds:

a. acetyl pyrimidine-Z-yl thiolester, acetyl 4- methylpyrimidine-Z-yl thiolester, acetyl 4,6-dimethyl-pyrimidine-Z-yl thiolester, (hereinafter the compounds having 4-methyl and/or 4,6-dimethyl substituents are omitted for simplicity, but they are natu rally included in the compounds of the present invention) propionoyl pyrimidine-2-yl thiolester, butyryl pyrimidine-2-yl thiolester, iso-butyryl pyrimidine- 2-yl thiolester, erotonoyl pyriimidine-Z-yl thiolester, 2,3dichlorobutyryl pyrimidinc-Z-yl thiolester, nvaleryl pyrimidine-2-yl thiolester, t-valeryl pyrimidine-2-yl thiolester, caproyl pyrimidine-2-yl thiolester, 5-hydroxylcaproyl=pyrimidine-2-yl thiolester, pentenyl-carbonyl pyrimidine-Z-yl thiolester {H- C=CH.(CH .COS(C,,N H octanoyl pyrimidine-2-yl thiolester, dodecanoyl pyrimidine-2-yl thiolester, hexadecanoyl pyrimidine-Z-yl thiolester, and the like; b. benzoyl pyrimidine-Z-yl thiolester, p-salicyloyl pyrimidine-Z-yl thiolester, p-nitrobenzoyl pyrimidine-2-yl thiolester, p-N',N'-dimethylaminobenzoyl pyrimidine-Z-yl thiolester, toluoyl pyrimidine-Z-yl thiolester, naphthoyl pyrimidine-2-yl thiolester, anthracene-carbonyl pyrimidine-Z-yl thiolester, pyritive group for amine, are particularly preferable as acylating agents for N-terminal free amino acids or N- terminal free peptides, that is, as active esters in peptide syntheses.

The pyrimidine derivative represented by the formula (I) is obtained by reacting a 2-mercapto-4-and/or 6-methyl-substituted or unsubstituted'pyrimidine represented by the formula (II) with a carboxylic acid or reactive derivative thereof with regard to the carboxyl group in an inert solvent in the'presence or absence of a coupling agent, as is clear from the reaction schema shown below. I

N -SH R;,COOH )-s c R,,

(Carboxylic acid N R or reactive R.

' derivative (ll) thereof) -(l) dyl-carbonyl pyrimidine-Z-yl thiolester, furoyl pyrimidine-Z-yl thiolester, and the like;

c. phenylacetyl pyrimidine-Ly] thiolester, p-methoxyphenylacetyl pyrimidine-Z-yl thiolester, cinnamoyl pyrimidine-Z-yl thiolester, 4-phenylbutyryl pyrimi- The pyrimidine derivativesrepresented by the formula (I) not only can easily be produced on commercial scale from inexpensive industrial reagents, as will be mentioned later, but also are stable and can easily be stored and handled. Moreover, the thiolester portrons. T

wherein R and R are as defined in the formula (I R is the residue group of an amino acid; and A is a protec- In the above reaction schema, R R and R are as defined in the formula (I).

The compound represented by the formula (II) is a known compound and can easily be obtained according to a known process using an inexpensive industrial reagent. For example, Z-mercapt-pyrimidine can easily be prepared from l,l,3,3-tetraethoxypropane and thiourea, and 2-meracpto-4,6-dimethylpyrimidine can easily be prepared from acetylacetone and thiourea, respectively, in the presence of hydrochloric acid as a catalyst.

Examples of the carboxylic acid or reactive derivative thereof with regard to the carboxyl group include straight chain or branched chain saturated or unsaturated aliphatic carboxylic acids, aromatic carboxylic I acids which may contain hetero atoms such as N, S and O, aralkyl carboxylic acids, amino acids wherein the functional groups such as amino group are properly protected, and reactive derivatives of these carboxylic acids with regard to the carboxyl group. The aliphatic carboxylic acids mentioned above may contain straight chain or branched chain saturated or unsaturated alkyl groups having 1 to 20 carbon atoms. Further, the carboxylic acids mentioned above may contain various substituents or properly protected functional groups.

More concretely, the following compounds may be included in the carboxylic acids;

a. aliphatic carboxylic acids: acetic acid, monochloroacetic acid, dichloroacetic acid, trimethylacetic acid,

propionic acid, acrylic acid, methacrylic acid, butyric acid, iso-butyric acid, 3-phenylhutyric acid, crotonic acid, 2,3-dichloropropane-l-carboxylic acid, valeric acid, trimethylmethane carboxylic acid,- caproic acid, 4-hydroxylpentanel -carboxylic acid, o-phenylhexane-l-carboxylic acid, caprylie acid, capric acid, lauric acid, palmitic acid, stearic acid, oleic acid, linolcic acid, and the like;

aromatic carboxylic' acids: benzoic acid, phydroxylbenzoic acid, p-aminobenzoic acid, pnitrohenzoic acid, p-N,N-dimethylaminobenzoic acid, toluic acid, naphthoic acid, anthracene-lcarboxylic acid, nicotinic acid, furan-3-carboxylic acid, salicylic acid, and the like;

c. aralkyl carboxylic, acids: phenylacetie acid, p-methoxyphenylacetic acid, p-chlorophenylacetic acid, p-cthylphenylacetic acid, p-nitrophenylacetic acid, y-phcnylpropionic acid, 3-phenyl-butyric acid,

cinnamic acid, 4-phenyl-n-valeric acid, 5-phenyl-n caproic acid, and the like;

(1. amino acids: a-amino acids of natural occurrence such as alanine (Ala-OH), arginine (Arg-OH), aspartic acid (Asp-OH), asparagine (Asn-OH), cystein (Cys-OH), cystine [(Cys) diiodotyrosine [Tyr- (I glutamic acid (Glu-OI-I), glycine (Gly-OH), histidine (His-OH), hydroxyproline (Hyp-OH), isoleucine (lle-OH), leucine (Len-OH), lysine (Lys- OH), methionine (Met-OH), norleucine (Nle-OH), ornithine (Om-OH), phenylalanine (Phe-Ol-I), proline (Pro-OH), serine (Ser-OH), threonine (Thr- OH), tryptophane (Trp-OH), tyrosine (Tyr-OH), val ine (VaLOH) and the like; B-and m-amino acids such as B-alanine, y-aminobutyric acid, e-aminocaproic acid and the like; synthetic and semi-synthetic amino acids such as oz-methylalanine and the like. (The symbols in the parentheses as well as those appear hereinafter are ordinarily used in the field of peptide chemistry. The protective groups therein are omitted for simplicity, as is the same hereinafter).

In the above-mentioned amino acids, as the protective groups for the functional groups such as amino group, there are, for example, a benzyloxycarbonyl group (Z-), a p-methoxybenzyloxycarbonyl group (pMZ-), a tert-butyroxycarbonyl group (t-BOC-), a tert-amyloxycarbonyl group (t-AOC), a phthaloyl group (Phth), a tosyl group (TOS--), a benzhydryloxycarbonyl group (BhOC-) and the like.

As the reactive derivatives of carboxylic acids with regard to the carboxyl group, there may be used all the known relative derivatives such as acid halides, acid anhydrides, esters, lactones, and acid azides of various carboxylic acids mentioned above. Particularly, acid halides such as acid chlorides and'acid bromides; acid anhydrides such as acetic anhydride, propionic anhydride, and benzoic anhydride; and admixed acid anhyrides suchas admixed alkylphosphoric anhydrides, admixed alkylcarbonic anhydrides and admixed anhydrides obtained from-a carboxylic acid and ethyl chlorocarbonate, are preferably employed.

The reaction between the 2-mercapto-pyrimidine represented by the formula (II) and the carboxylic acid or reactive derivatives thereof is carried out in an inert solvent. i

When'afree carboxylic acid is used in the reaction, it is necessaryto add a coupling agent in the reaction system. As the coupling agent, there may be used any known coupling agents, which are usually employed in esteriiicatioif" reaction, such as dicyclohexylcarbodiimide, N,N-diisopropylcarbodiimide, carbonyldiimidazole, N-cyclohexylN-morpholinoethylcarbodiimide and the like.

When a reactive derivative of carboxylic acid is used, it is unnecessary to use a coupling agent.

As the inert solvent used in the above reaction, any solvent is usable so far as it is inert to the reactants and the reactionproduct and it can dissolve or suspend l0 vent employed.

The reaction time depends on the kind of reactants and the reaction temperature employed, and is generally over 30 minutes. In most cases, it is sufficient to react upto 24 hours. But the reaction time as mentioned above is not critical and the reaction may be conducted for less than 30 minutes or over 24 hours.

After completion of the reaction, the reaction solu tion is purified by a conventional process, for example, by distilling off the solvent followed by recrystallization to obtain the desired pyrimidine derivative represented by the formula (I).

Since the reaction generally proceeds almost quantitatively without accompanying side reactions, the pyrimidine derivative represented by the formula (I) can 25 be obtained extremely high in. purity even from unpurified starting materials. Further, the thus obtained pyrimidine derivatives can be used in the form of the re action solution as it is without being isolated and puri-' fled in acylation of amines and the like as hereinafter 1 3O mentioned in detail to yield highly pure acylated products.

The novel pyrimidine derivatives represented by the formula (I) are quite useful as acylating agents in acylating compounds such as amines, hydrazines, alcohols and phenols, and particularly useful for compounds having hydroxyl groups together with amino and/or imino groups in acylating selectively the amino and/or imino groups therein even though the hydroxyl groups therein are not protected by ordinary protective 40 groups. Further, the pyrimidine derivatives of the present invention are also quite useful as acylating agents, i.e; active esters in peptide syntheses, since they react with N-terminal free amino acids having protected carboxyl groups to obtain compounds having peptide 5 bonds in high yield without racemization and side reactions under certain conditions with extremely faster reaction rate than the known active esters such as carboxylic acid derivatives.

In the next place. a process for acylating, including peptide synthesis, various amines, hydrazines, phenols and alcohols by using as acylating agents the pyrimidine derivatives represented by the formula (I) is explained below.

The acylation of a compound having amino and/or imino and/0r hydroxyl groups or a salt thereof comprises reacting said compound with the pyrimidine derivative of the formula (I) in an inert solvent in the presence of absence of a base, as shown by the follow- 0 ing reaction schema:

(Ill ('IV In the above schema, R R and R are as defined in the formula (I and H in the formula (III) is a hydrogen atom in the amino or imino or hydroxyl group; and 'X' is a residual group of the compound formed by removing one hydrogen atom from the amino or imino or hydroxyl group thereof.

The compounds represented by the formula (III) include univalent amines, imines, alcohols or phenols, or those having two or more amino and/or imino groups, or those having two or more hydroxyl groups, and further they may be compounds having both one or more amino and/or imino groups and one or more hydroxyl groups. When the compound of the formula (III) has plural functional groups and all of the functional groups are to be acylated, the pyrimidine derivative of the formula (I) is used in an amount corresponding to the numbers of the functional groups. The hydroxyl group mentioned above means both alcoholic and phenolic hydroxyl groups.

Examples of the compound having amino and/or imino and/or hydroxyl groups represented by the formula (III) include a wide scope of compounds such as aliphatic, alicyclic, aralkyl, aromatic and heterocyclic A. Methylamine, dimethylamine, ethylamine, ethylene diamine, diethylenetetramine, ethanolamine, isopropylamine, butylamine, t-butylamine, N-ethyl-N-fi hydroxyethylamine, octylamine, laurylamine, and the like.

B; Cyclohexylamine and the like.

C. Benzylamine, p-chlorobenzylamine, pmethoxybenzylamine, p-nitrobenzylamine, 3- phenylpropylamine, 3-(p-methoxyphenyl)- 4 propylamine, and the like.

D. Aniline, N-methylaniline, p-methylaniline, paminophenol, p-methylaminophenol, toluidine, xylidine, o-carbomethylaniline, p-phenetidinc, diphenylamine, a-(or B-)naphthylamine, 4-aminonaphthol,

and the like.

E. Ethyleneimine, pyrrolydine, pyrazole, indole, and

the like.

F. Hydrazine, phenylhydrazine, 2,4-dinitrophenylhydrazine, N-methyl-N-phenylhydrazine, and the like.

G. Amino acids of natural occurrence having free amino and/or imino groups and protected carboxyl groups and synthetic and semi-synthetic amino acids: a-amino acids of natural occurrence such as Ala-OH, Arg-OH, Asp-OH, Asn-OH, Cys-OH, Glu-OH, Gly- OH His-OH Hyp-OH, Ile-OH. Leu-OH, Lys-OH, Met-OH, Nle-OH, Orn-OH, Phe-OH, Pro-OH, Ser- OH, Thr-OH, Trp-OH, Tyr-OH, ValOH and the like; 8- and w-amino acids such as B-alamine, 'y-aminobutyric acid, e-aminocaproic acid and the like; synthetic and semi-synthetic amino acids such as a-methylalanine and the like; peptides obtained by coupling reaction of two or more amino acids. (The protective groups therein are omitted for simplicity, as is the same hereinafter).

The carboxyl groups in these amino acids and peptides may be protected by alkyl esters such as methyl ester, ethyl ester, and the like, or salts such as sodium salt, potassium salt, magnesium salt and the like, or acid amides, as is the same as in known processes for synthesizing peptides. After completion of the reaction, these protective groups for the carboxyl groups or those derived from the compound of the formula (I), e.g., protective groups for amine, can be removed by a known process, if necessary.

H. Saccharides and steroids such as 2-amino-l,6- anhydro-2-deoxy-,8-D-glucopyranose, L- glucosamine, methyl-3-amino-B-L-xylopyranoside, and the like.

3. Methyl alcohol, ethyl alcohol, isopropyl alcohol, amyl alcohol, octyl alcohol, lauryl alcohol, phenol, catheehol, naphthol, benzyl alcohol, eyclohexanol, and the like.

In the compounds represented by the formula (III), the compound having amino and/or imino groups may be subjected to acylation reaction in the form of a free amine or imine or a salt thereof such as, for example,

hydrochloride, hydrobromide, hydroiodide, sulfate,

sulfite or the like. In case the compound is subjected to the reaction in the form of a salt, it is necessary to add a base as a deacidifying agent to the reaction system. As the deacidifying agent, there may be used any conventional deacidifying agents, for example, organic tertiary amines such as triethylamine, N-alkylmorpholine, N,N-dialkylaniline, pyridine, xynoline and the like or inorganic bases such as a hydroxide, carbonate or bicarbonate of alkali metal, for example, potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate and the like.

The reaction between the compound of the formula (I) and the compound of the formula (III) is carried out in an inert solvent.

As the inert solvent, any solvents which are inert to the reactants and the reaction product may be used. Examples of the inert solvent include dioxane or aqueous solution thereof, chloroform, methylene chloride, ethyl acetate and the like. When dioxane or ethyl acetate is used as the solvent, liberated pyrimidine of the formula (II) in the coupling reaction is precipitated.

The above-mentioned reaction may generally be carried out at a temperature between 50 and C. In case the reaction is carried out below about -20C, the acylation .of the hydroxyl group is inhibited substantially 100 percent. Therefore, the esterification reaction according to present acylation reaction must be carried out at least about 20C or higher. Generally the esterification reaction is carried out at room temperature or higher. When selective acylation of the amino and/or imino groups is required to the compound having both the hydroxyl group and amino and- /or imino groups, the reaction is preferably carried out below 2()C, since the acylation of the hydroxyl group does not substantially take place below 20C. In acylating Saccharides or steroids having both hydroxyl groups and amino and/or imino groups, and selective acylation of the amino and/or imino groups being required, it is necessary to protect the hydroxyl groups by protective groups such as a benzyl group, a carbobenzoxy group and the like according to known processes. On the contrary, in the present process it is not neces- :9 sary to protect the hydroxyl group by any protective group, since selective aeyl a'tioiiof the amino and/or imino groups therein isppssible belowabout 20C.

In case the pyrimidine derivative of the formula( l-a) 5 is' used as a reactive ester-in peptide synthesis *eig. the coupling reaction of the compound of thefor kiwi-iii and 'N-lterminal free 'amirio' aci'd 'pe'ptidei' i t ispr e'fe ble to carry-out thr'ea'ction at 50 and 6 C.-But theflic'yl tioned above arenorci' itica g In the aoylation reaction mentioried abov tri -jihadtion is' completed inmost ea'se'within" 3(Yiniriutes, bi within6 hou'r'sat the longetiAeeirdihg fothe steam process, thereaction rdc'eedswit extremely rariaction rate even at a low temperature. Howeverft'he ac"- ylation of phenols or alcohols takes relatively longer reaction time and the yield thereof isalso relatively'low when compared with the reaction of .amines..-=Inthe above case, there may be used a known catalyst for esterific'ation such as acetic acid, Z -hydr Xypridine and the like. p: I

In the acylation reaction using the pyrimidine deriv'a tiveof the formula ('I),"there are many advantages as mentioned below: a V

Compounds having amino and/or droxyl groups are easilyacylate'd under mild etinditio s to yield the corresponding amides (or imides), peptides or esters in high yield.

The pyrimidine derivatives of the formula (I) have little selectivity to the reactantsand easily react with any amines (or imines), hydrazines, alcohols or phenols. l y

Contrary to the" known active iesters have" mostly selectivity to l l-termiiial'free amino acids or peptides in the coupling.reactiontherewith. the pyrimidine derivatives of the formula (I) do not show such selectivity and easiljreactwitli an y' am ino i icids or pep- :Ii, 1." I

In the acylation ofithe 'compou-nds'having amino and- /or-1imino and/or hydroxylegroup's.:with-got her= active groupsisuch as ,canboxyl or. imida zole-,:=thepyrimidinederivatives .of theformula ,(-.I)1can reactpreferentia-lly' and-selectively with :thev amino ;a-nd/'or imino and/01 11)! droxyl groups, which cannot: begexpectedin thexknown acylating agents.

In the acylation of .thecompounds having bothamino. and/or imino groups and hydroxyl groups using the py rimidinc derivatives of the formula (I), the amino iiiid /or imino groups therein can' selectively be acylated it. YPLIWHI-H ion 'temp eratures menwithout protecting thehydroxyl groups by c onf,

ducting the reaction below about 20C. a According tothe acylatiomrea'ction using the pyrimidine derivatives of the formula (I), the purification of the acylated products is-extremely e'asy. i

In the acylat'ion reaeti'r in using thepy rimidinederivii- 1 tivcs of the formula (I), Z-mcrCap'tO-py' rimidine"or a derivative thereof represented by the formula (II) is produced with the proceeding of the reaction and is liberated and is sometimes precipitated from the reaction solution containing the acylated product. Thus the separation of said 2-mercapto-pyrimidine of the formula (ll)' is easy and 'further the remaining rate of 'sai'df 2mercapto-pyrimidine in the reaction solution com taining the acylated product very low. Further. since the Z-merCapto-pyrimidineofthc formula (II) is an amphotcric compound and is easily dissolvedin both an acid and an, alkali, even though it is retained in there-, action solu tion containing the acylated prod uct. it can easily be removed by washing the reaction solution equipped same procedure as mentioned above.

Although purification of the produced peptide is most important problem in peptide synthesis, the pro duced peptide can be obtained in 'hi gh purity and in highyield according toi -the process using the pyrimidine derivative of the formula (I) as an active ester, sincfejthe produced Z-rrier captQ- pyrirnidine of the for: rhula fll ean easily L be removed as mentioned above. Inth e peptide synthesis of optically active materials, itis-importantto conduct the, reaction with maintaining the qptical =activitiesof the materials withoutcausing racerniz ationaAccording to the iprocess using the pyrimidine derivative of the -formula (I) as an active ester, a peptide bond canieasilyibe formed-with extremely greaterreaction-rate than that; using other known active ester without'cau'sing racemiiz'ation or without accompanying side reactions under certain reaction conditions such as mild conditions, for example, conducting therzictiori under relatively low temperature.

" The accompanying drawings are the 'infraredspectra of the yrimidine derivativesmepresented by the for rriaia 1 "('FIo.f1 f Fiojj g d those or the acylated pr' o tsfac 'cord ng to the processes of Examples menhe reinbelow trio. :5; R G/. 16),

sii

Procedures for I preparing 2 -mercapto-4- and/or 6-m ethyl-substitutedv or unsubstituted. pyrimidines which are starting materials for production of the pyrimidine derivatives represented by the formula (I), are explainedbelow with reference to referential examples.

,RERER NTIAL EXAMPLE]:

g f Sy nithesis ofZ rnercapIb pyrimidine 'A s'olutionbfbl g (0.80 mole) "ofthio'urea in 500 ml ofe'thandl'was charged into a Z liter three-necked flask I i th a stirrer and a reflux co ndenser, and 20O ml of ddnceritrated hydrochloric acid was added to the solutid ,twli'ereby liquid became homogenous after :l'his liquid was mixed with 176 g (0.80 in le xpf ,3,3;tetraethoxypr pane,andthe resulting mixturegwas reacted under reflux for about 1 hour. After completion of the reaction, .the reaction liquid was cooled to l0C in an ice bath and maintained at said temperature for 30 minutes to deposit Z-mercaptopyrimidine hydrochloride in the form of yellow crys tals. The crystals were collected in a Bu chner funnel, washed with 100 ml of cold alcohol and then dried at room temperature to obtain 89 g of crude Z-mercaptopyrimidine hydrochloride in yield .of 75 percent.

The crude 2-mercapto-pyrimidinc hydrochloride 25 g, 0.17 mole was suspended in 5(l ml of water. and the resulting suspension was adjustedto pH 7 to X by addition o f 27 nil ofa'JZI) "/6 aqueoiis sodium hydroxide solution, wheieby 2-riiercapto pyrirnidine was precipitated This Emercapt;z pyrimidinc was recovered byfiltration witha Buchnc r' lfunncl, \x'ziished writh 50 ml of cold water and then recrystallized from a solution comprising300v ml of water and 300 ml of ethanol to obtain l9 g of Z-mercapto-pyrimidine in yield of percent.

Elementary analysis:

I CW1) /(r NW3 SUM Calcd. for C,H N S 42.84 3.59' 24.98 28.5) Found 42.91 3.6x 24.93 234s REFERENTIAL EXAMPLE Synthesis of 2 -mercapto-4,6-dimethyl-pyrimidine" I Thiourea (76 g, 1.0 mole) was suspended in a solu tion f'l20 g (1 12 moles) of aeetylac'etone in 2,500 ml of ethanol. The resulting suspension was mixed with 250 ml of concentrated hydrochloric acid. andthen reacted under reflux for 2 hours. After completion of the reaction, the reaction liquid was cooled, whereby beautiful yellow needle-like crystals of 2 -mercapto-4,6- dimethyl-pyrimidine hydrochloride were formed. The reaction liquid was allowed to stand for a-day to deposit sufficiently the crystals, which were then recovered by filtration and dried to obtain I40 g of 2-rnercapto-4,6- dimethyl-pyrimidine hydrochloride in yield of 80 percent.

To the filtrate after recovery of the above-mentioned pyrimidine hydrochloride were again added I10 g of acetylacetone. 76g of'thiourea, 100 ml of ethanol and I50 ml of concentrated hydrochloric acid, and the resulting mixture was subjected to filtration and drying to obtain 158 g of Z-mercapto-4,6-dimethylpyrimidine hydrochloride in yield of 90 percent. The filtrate in this case was again subjected to the same operation as above to obtain I48 g of 2-mercapto 4,6- dimethylpyrimidine hydrochloride in yield of 84 percent.

The above-mentioned dimethylpyrimidine hydrochloride (200 g, 1.13 moles) was suspendedin 400 ml of water, and the resulting suspension was heated to about 40C, while gradually adding thereto 70 ml of a 20 aqueous sodium hydroxide solution, whereby the 2-mercapto-4,6- dimethyl-pyrimidine hydrochloride was completely dissolved. This solution was adjusted to pH 4.5 to 5.0 by gradual addition of a 20 71 aqueous sodium hydroxide solution, whereby pale yellow crystals of 2 mercapto 4,6-dimethyl-pyrimidine were precipitated. The reaction liquid was allowed to stand for a day at room temperature to sufficiently deposit the crystals, which were then recovered by filtration and dried to obtain 1 17 g of2-mercapto-4.(v-dimethyl-pyrimidine in yield of 74.3

percent.

Elemcntury analysis:

(U 1 HUA) SIJ) (alt-d. for (,,H,.N. ,S l .40 575 I998 Found 5 I .52 5.75 20.03 22.75

Procedures for producing the present pyrimidine derivatives represented by the formula I) are illustrated below with reference to examples.

Examples 1 to 9 relate to processes for preparing aeyl 4- and/or o-methyl-substituted or unsubstituted pyrimidine-2-yl thiolesters.

, EXAMPLE '1 Synthesis ofacetyl pyrimidine-'Z-yl thiolester Z-Meieapto-pyrimidine (21.24 g, 0.02 mole) was suslpended in 20ml of dioxane, and I0.2 g (0. l0 molelof acetic anhydride was dropped into the resulting mixture at room temperature and reacted. After 20 hours the solution became completely transparent and the reaction was completed. Then the solvent and the excess acetic ,anhydride were distilled off under reduced pressure from thereaction s0lutiQr1. Theresidue was recrystallized from an benzene-petroleum ether solventto obtain 2.20 g of acetyl pyrimidine-231ithiolester;.yield, 72 percent;,m.p. 5 8?C i Elementary analysis:

' w) hm) i H s 71 Calcd. for C H,;ON S 46.74 392 I817 20.79 Found 46.88 4.08 .1513 20.87

FIG. I showsthe infrared spectrum of acetyl pyrimidine-Z-yl' thiolester. The infrared spectrum shows the presence of I in the thiolester bond 1,700 cm) and the pyrimidine .Usinga-similarprocedure to Example I, 2-mercapto- 4,6-dimethyl-pyrimidine was reacted with acetic anhydrid'e. After distilling off the solvent and recrystalli-. zation, 16.6 g of -acetyl 4,6-dimethy-pyrimidine-2 y]= thiolester having a melting pointof I9.52I.OC' was obtained in yield of-9-l percent.

Elementary analysis:

Calcd.forC1H,,,()N S "S173 5.53 15.37 i759 Found 5.43 17.54

52:50 was FIG. 2 shows. the infrared spectrum .of .acetyl 4,6-dimethyI-pyrimidinc-Z-yl thiolester. The infrared spectrum shows the presence of in the thiolester bond 1,708 chi andthe pyrimidine ring 1584 and 1.260 cm EXAMPLE 3" Synthesis-of henzoyl pyrimidine-Ly] thiolester After dissolving I I'.'2 g HIIIfl mo'le') of fZ-mercaptopyrimidine in a solution of 20 m1 of water containing 6.6 g of potassium hydroxide, 15.4 g (0.11 mole) of benzoyl chloride in 40 ml of ethyl acetate was dropped with stirring into the resulting mixture under ice cooling, and reacted. After allowing the reaction solution to stand for a day at room temperature, it was washed three times with an aqueous saturated sodium bicarbonate solution, twice with a 2N aqueous hydrochloric acid solution and twice with a 10 70 aqueous sodium chloride solution. The ethyl acetate layer was dried over anhydrous sodium sulfate and the ethyl acetate was distilled offv The residue was recrystallized from ether to obtain 14.1 g of benzoyl pyrimidine-2-yl thiolester; yield, 65 percent; m.p. 54 55C.

Elementary analysis:

C( /r) HU/r) l l (7!) Calcd. for H ON S 61.09 3.73 12.95 14.83 Found (11.13 3.84 12.76 14.85

FIG. 3 shows the infrared spectrum of benzoyl pyrimidine-Z-yl thiolester. The infrared spectrum shows the presence of in the thiolester bond 1,673 cm) and the pyrimidine ring 1,552 and 1,382 emf).

EXAMPLE 4 Synthesis of benzoyl 4,o-dimcthyl-pyrimidine-2-yl thiolester Using a similar procedure to Example 3, Z-mercapto- 4,6-dimethyl-pyrimidine was reacted with 'benzoyl chloride. After washing, distilling off the solvent and recrystallization, there was obtained 17.8 g of benzoyl 4,6-dimethyl-pyrimidine2-yl thiolester; yield, 73 71'; m.p. 76 77C.

Elementary analysis:

C(71) HUK') NW1) S('/r) Calcd. for C H -ON S 63.91 4.95 1 1.47 13.12 Found 63.89 4.90 11.39 13.12

FIG. 4 shows the infrared spectrum of benzoyl 4,6-dimethyl-pyrimidine-2-yl thiolester. The infrared spectrum shows the presence of After dissolving l 1.2 g (0.10 mole) of 2-mercaptopyrimidine in a solution of 6.6 g of potassium hydroxide Elementary analysis:

Calcdv for C H ON S 64.44 4.16 11.56 13.23 Found 64.52 4.32 1 1.39 13.34

FIG. 5 shows the infrared spectrum of cinnamoyl pyrimidine-2-yl thiolester. The infrared spectrum shows the presence of in the thiolester bond 1,659 cm) and the pyrimidine ring (1,550 and 1,385 cm).

Example 6 Synthesis of N-benzyloxycarbonyl-glycine pyrimidine-Z-yl thiolester 2-Mercapto-pyrimidine (1.12 g, 0.01 mole) was suspended in 50 ml of ethyl acetate, and 2.21 g (0.01 mole) of N-benzyloxycarbonylglycine was added to the resulting suspension and successively 2.06 g (0.01 mole) of dicyclohexylcarbodiirnide was added thereto with stirring at 0C and reacted. Within 5 minutes dicyclohexylurea began to precipitate and deposit, and Z-mercapto-pyrimidine was consumed completely in about 4 hours. After allowing the reaction solution to stand overnight at 0C, the precipitate of dicyclohexylurea was filtered off and the filtrate was washed twice with 30 m1 of an aqueous saturated sodium chloride solution and dried over anhydrous sodium sulfate followed by distilling off ethyl acetate under reduced pressure at room temperature to yield oily substance. The oily substance was dissolved in a small amount of a ethyl acetate-ether solvent and allowed to stand to obtain pale yellow crystals of N-benzyloxycarbonyl-glycine-pyrimidine-2-yl thiolester; yield, 88 percent (2.67 g); m.p. l30-l31C.

Elementary analysis:

Synthesis of N-benzyloxycarbonyl-glycine pyrimidine-Z-yl thiolester After 0.02 mole of 2-mercapto-pyrimidine was dissolved in m1 of methylene chloride, 0.02 mole of N-benzyloxycarbonylglycine was added to the resulting solution, and then 0.02 mole of dieyclohexylcarbodiimide was added thereto under ice cooling and reacted for 3 hours. After cooling the reaction so- FIG. 7 shows the presence of NH(3.220 cm),

lution sufficiently, the produced precipitate of dicyclohexylurea was filtered off. The methylene chloride 1 in the filtrate was distilled off under reduced pressure at room temperature and the residue was recrystallized from a ethyl acetate-petroleum ether solvent. The obin the ester bond (1.705 cm), the pyrimidine ring tained pale yellow crystals have a melting point of (1,587 and 1.520 cm) and lf-l3lC, which was identified as the same com pound as obtained in Example 6 from the results of elementary analysis. The yield of it was 90 percent.

EXAMPLE 8 l g C 2-Mcrcapto-4.o-dimethyl-pyrimidine (0.01 mole) was suspended in 50 ml of ethyl acetate and 0.01 mole 1,244 cm' Table l NZamino acid Run Z-an1ino 4.6-dimethyl- Yield M.P. Elementary analysis (71) No. acid pyrimidine-Z-yl thiolester (71 (C) C H N N CulCd. 59.11 5.54 12.16 9.221 1 z 1.- Zl.A1aS- s5 110 111 Ala-OH CHH Found 59.25 5.63 12.23 9.18

N Calcd. 65.50 5.50 9.97 7.61 2 7. 1. Z-l.Pl1L:S- 92 139-140 Phe-OH CH Found 65.70 5.65 9.87 7.70

N .1 Calcd. 61.99 6.50 10.86 8.27 3 7.L- L-l.eu-S 83 1130-1135 l.euOH

' H Found 6 .08 (1.47 10.76 112s N 4 Calcd. 59.11 5.54 12.16 9.2x 4 ZYD ZDl.A1a- 147 104-105 l.-Ala-()H C11,. Found 50.40 5 67 12 12 9.26

T "Z: a henzyloxycarbonyl group CH:-Ol

of N-benzyloxycarbonyl-amino acid as listed in Table EXAMPLE 9 l was added to the resultmg suspens1on, and then 0.01 Synthesis of NbenwlowcarbonyHjalaninfi mole of dicyclohexylcarbodiimide was added under ice cooling and reacted for 2 hours. After completion of the reaction. the dicyclohexylurea was filtered and the ethyl acetate in the filtrate was distilled off under reduced pressure at 30C. The residue was recrystallized from an ethyl acetate-petroleum ether solvent to obtain the corresponding N-benzyloxycarbonyl-amino acid 4,6-dimethyl-pyrimidine-2-yl thiolester. Table 1 shows the obtained results.

FIG. 6 and FIG. 7 show the infrared spectra of the resulting compounds of Run Nos. 2 and 3 in Table 1.

FIG. 6 shows the presence of NH(3.220 cm),

in the ester bond (1,714 cm). the pyrimidine ring (1.587 and 1.522 cm) and 4.6-dimethylpyrimidine-Z-yl thiolester N-benzyloxycarbonyl-L-alanine (0.05 mole) and 0.05 mole of triethylamine were dissolved in 100 m1 of methylene chloride. and 0.05 mole of ethyl chlorocarbonate was dropped in the resulting solution under cooling at 5C. After 15 minutes, a solution of 0.06 mole of 2-mercapto-4,6-dimethy1-pyrimidine in 50 ml of methylene chloride was added to the resulting solution and reacted for 2 hours. The thus obtained reaction solution was washed with water and then the solvent was distilled off under reduced pressure to obtain pale yellow oily substance. When said substance was recrystallized from an ethyl acetate-petroleum ether solvent, the obtained crystals showed a melting point of 1 l01 1 1C. The data of elementary analysis showed that the obtained crystals were the same compound as that obtained in Example 8, Run No. l. The yield thereof was percent.

The following Examples 10 to 13 relate to the acylation of amines. hydrazines, alcohols and phenols using the pyrimidine derivatives represented by the formula EXAMPLE and 2-mercapto-pyrimidine was deposited with the progress of the reaction. After completion of there-action, the 2-mercapto-pyrimidine was filtered off and the filtrate was washed with an aqueous saturated sodium bicarbonate solution, an aqueous saturated sodium chloride solution, a 0.5 N aqueous hydrochloric acid solution and an aqueous saturated sodium chloride solution, respectively, and then dried over sodium sulfate. After removing ethyl acetate by distillation, the residue was recrystallized from an ethyl acetatepetroleum ether solvent to obtain the corresponding N-acyl amine or N-acyl hydrazine. Table 2 shows the results obtained.

FIG. 8 FIGv 13 show the infrared spectra of N-tbutyl-acetamide (No. 2), N-acetyl-B-naphthylamine (No. 4), N,N-diethyl-acetamide (No. 5), N- acetylpiperidinc (No. 6), N-allyl-sinnamic acid amide (No. 7) and N-benzoyl-t-butylamine (No. 9), respectively.

FIG. 8 shows the presenceof NH(3,310 cm") and in the amide bond (1,642 cm).

FIG. 9 shows the presence of NH (3,270 cm) and in the amide bond 1,664 cm U 10 shows the presenceof in the li C-N "(l; 6 3 2 cm U.

FIG. 11 shows the presence of in the ,0 ll CN FIG. 12 shows the presence of NH (3,300 cm and in the amide bond (1,655 cm").

in theamide 'bond (1,632cm).

' Table 2 Amine or N-ucylaminc or 't-But luminc Amine or hydrazine Run Pyrimidine No. derivative p-'l'oluidinc 9 t-Butylaminc Il)Il A r I l Phcnyl- 'f '7 hydrazine I DL-Alanine y I, V l 1 ethyl ester DLH,-,C. .OOCCH NH I Run Yield M.P. B.P. Elementary alysis (71) '1 N0. ('71) (C) C 1 98.5 151 151.5 Culcd. 72.46 7.43" 9.39

Found 72160 1 7.50 9.30 2 98.5 97 97.5 Culcd. 62.57 1 11.37 .12.15.

Found 62.64 11.41 12.10 i 3 95.6 128 130 Culcd. 63.98 6.71 18.65 1 Found 63.82 6.64 18.77. 4 )3 134 136 1 CillCLl. 77.81 5.98 7.56

Found 77.80 5.90 7.63 5 98.1 185 186 Calcd. 62.57 11.37 12.16 Found 62.58 11.45 12.18 6 )5 8 226 227 Culcd. 66.10 10.30 12.57

Found 66.34 10.30 12.81 7 .0 92 Ci\lCt1. 76.98 7.00 7.48 Fouhd 77.01 7.08 7.30 8 85 158 159 ClllCd. 79.59 6.20, 7 6.63 Found 79.65 6.27 6.55 9 )6 135 Calcd. 74.54 8.53 7.90 Found 74.62 8.59 8.05 10 '98 168 169 Caled. 73.56 5.70 13.20 Found 73.63 5.80 13.17 11 98 72.5 73 Y Calcd. 65.14 6.83 6.33 Found 65.36 6.87 6.28

EXAMPLE 1 l ml of ethyl acetate to the resulting mixture, the esterifiQ cation was carried out under the conditions listed in "l able 3 Reaction conditions 7 Run Alcohol or Ester No. phenol Table 3. In case 0.01 mole of acetic acid or 0.01 mole of Z-hydroxypyridine was used as a catalyst, the reaction was carried out similarly. After completion of the 45 reaction, the precipitated Z-merCaptO-pyrimidine was filtered off and the filtrate was purified by the same procedure as Example 10 to obtained the corresponding ester. Table 3 shows the obtained results.

Yield (/1) cmcooH-Qu -25% -50% 20-25% 20-25% 4H hm. 1.! hrs. 103C 24 hrs. 24 hrs.

' 12 hrs.

1 [lNziphthol 1 271C 1 23.7 11.! 45.5 502 O I. 2 Phenol 0 4- ('11.. I 11.4 20. 3.1.7 470 am 0 Ben/ 1 alcohol (H -o 3-111. 55.: m 7 .x 7. 7 z

4 n-llut \l alcohol 00 4 7% H r.

Acetyl pyrimidine-Z-yl thiolester (0.01 mole) ob tained by using the same procedure as described in Example l was dissolved in 20 ml of ethyl acetate, and

0.01 mole of the compound as listed in Table 4 was dissolved in the resulting solution. After addition of ml of ethyl acetate to the resulting mixture, the reaction was carried out at 30C or at C for minutes. After completion of the reaction, the precipitated Z-mercapto-pyrimidine was filtered off and the filtrate was washed and recrystallized by the same procedure as described in Example 10. Table 4 shows the ob tained results.

and the hydroxyl group are aeylated, although the latter is in a small amount, at 20C because of the presenee of the absorption band near 1,710 cm due to the ester bond.

EXAMPLE l3 Benzoyl 4,6-dimethyl-pyrimidine-2-yl thiolester (2.44 g, 0.01 mole) obtained by the process of Example 4 was reacted with the amine as listed in Table 5 in ethyl acetate using a similar process to Example 10 to yield the benzoylated product. After completion of the reaction, the precipitated 2-mercapto-4,6- dimethylpyrimidine was filtered off and the filtrate was Table 4 Run Starting Acetylated Yield ('7!) No. compound compound 30C 20C 1 HOCH. .CH. .NH. HOCH. .CH NHC CH; 100 93.0

0 ll C-CH 2 H()(H. .('H NH('. ,H,, HOCHQCHZN 100 99.3

o 3 H0-- NH HO-Q NHCH;, 96.5

FIG 14 and FIG 15 Show the infrared Spectra of washed and recrystallized using the same procedure as acewk'dted I84] rdmx' eth lamina (Run NO Hand acet described in Example 10. Table 5 shows the obtained y y y i results. In Table 5, Run Nos. 5 and 6 were benzoylatcd ylated N-ethyLB-hydroxyethylamine (Run No. 2). ln It C 2 s th esence of the absor tion due to the f i f g was Shown 662 u, in HG. 16 shows the infrared spectrum of N-bcnzoyl the former coripound and at l 620 cmfliin the ham aniline (Run No. 3). The infrared spectrum shows the f H 3.210 rn and compound. The infrared spectra further show that the prucnu' 0 N l L 1 amino or imino group is selectively acylated at 3()C 1 because of the absence of the absorption band due to the ester bond and that both the amino or imino group in the amide bond (1,625 cm).

Table Run Yield M.P. Elementary analysis ("/1 No. Amine N-acylaminc (/1) (C) C H N O Caled. 74.54 8.53 7.90 1 Dicthylammc (C. ,H .NC 97 Oily Found 74.60 8.70 7.91

. W Calcd. 74.54 8.53 7.90 2 LButylumme (CH );,(NH-( Q 100 l35 Found 74.42 8.60 7.9]

O I ll out-t1. 79.16 5.62 7.10 3 Aniline -NH-C- 99. 163.0 Found 79.2] 5.77 7.I(l

O y Calcd. 76.15 7. 7.40 4 Plpcrldinc N -C@ 99.4 Oily- Found 76.20 7.98 7.41

1? 5 N-ethyl-B- C Q Called. 68.36 7.82 7.24

HOCH- 1CH N\ 97.6 hydroxyethylaminc H Found 68.39 7.89 7.22

O ll Caled. 65.43 6.7] 11.47 6 [3-Hydroxyethylamme HO-CH CH NH-C Q I00 ()ily Found (15.49 6.78 8.4 I

The following Examples 14 l9 relate to the use of the pyrimidine derivatives represented by the formula (l-a) as acylating agents in the acylation of N-terminal free amino acids or peptides. that is. the peptide syntheses.

EXAMPLE l4 Z-MercaptO-pyrimidine (0.02 mole) was reacted with 0.02 mole of N-benzyloxycarbonyl-glycine using the same process as described in Example 6. The produced precipitate of dicyclohexylurea was filtered off and the filtrate was divided into two portions.

One of them was purified using the same procedure as described in Example 6 to obtain N-benzyloxycarbonyl-glycinc pyrimidine-Z-yl thiolester. the same compound as obtained in Example 6, in yield of 88 percent.

The other of them was used for the peptide synthesis. Glycine ethyl ester hydrochloride (0.01 mole) and 0.01 mole of triethylamine were added to the other portion of the reaction solution and reacted at 0C. The reaction took place soon and triethylamine hydrochloride and Z-mercapto-pyrimidine were precipitated with the progress of the reaction. After reacting two hours, the precipitates were filtered off and the filtrate was washed each two times with a saturated aqueous solution of sodium bicarbonate, a 0.5 N aqueous solution of hydrochloric acid and a saturated aqueous solution of sodium chloride and dried over anhydrous sodium sulfate. After removing the ethyl acetate by distillation from the resulting solution, there were deposited crystals, which were recrystallized from an ethyl acetatepetroleum ether solvent to obtain the dipeptidc of the formula.

wherein Et is an ethyl group; m.p. 83C; yield. 95 percent.

Elementary analysis:

Calcd. for C ,H n z Found EXAMPLE 15 EXAMPLE 16 To the reaction solution of N-protected amino acid pyrimidine-Z-yl thiolester obtained by reacting 2-mercapto-pyrimidine with the N-protected amino acid listed in Table 6 using a similar process to Example 6, the amino acid ester hydrochloride listed in Table 6 was added and reacted for l3 hours using the same Table 6 N-protected amino Amino acid Yield Run N-protected acid pyrimidine-2- ester (hydro- Dipeptide ('71 No. amino acid yl thiolester chloride) Found 67.58 7.14 6.61 103- Calcd. 62.62 7.74

Found 62.91 7.75 Caled. 64.47 6.5) 6.54 I52 428.5

Found 64.45 6.83 6.43 "25.9 Called. 60.70 7.1) 8.33 166.8 ((=l, EtOH) 336.4

Found 60.61 7.19 8.20 24.3 Calcd. 61.70 7.48 7.9) 10. (C=l. EtOH) 350.4

Found 61.68 7.44 7.98

l6 7.-L-Leu-OH Z-L-Leu-S- L-Phe-OEt Z-L-Leu-L-Phe-OEt )6 21.7 Called. 68.16 7.32 6.38 94.5 (C=l. EIOH) 440.5

Found 68.14 7.41 6.40

*l Phth: a phlhaloyl group Gimme-)2! *2) EtOH: eth \l alcohol *3) D.M.l".: dimeth lfimnumide *4) Me: a melh l group EXAMPLE 17 as described in Example 14 to yield the corresponding I i )x/- 1 v 2-Mercapto-4,6-dimethyl-pyrimidme (0.01 mole) pepude Flam 7 7 the Obtdmed results was suspended in 50 ml of ethyl acetate, and 0.01 mole of the N-protected amino acid listed in Table 7 was added to the resulting suspension. Further, 0.01 mole of dicyclohexylcarbodiimide was added to the resulting mixture under ice cooling and reacted for 3 hours to obtain the active ester, N-protected amino acid 4,6-dimethyl-pyrimidine-2-yl thiolester. After completion of the reaction, the produced dicyclohexylurea was filtered off and to the filtrate 0.01 mole of the amino acid or peptide ester hydrochloride listed in Table 7 and 0.01 mole of triethylamine were added and the coupling reaction was carried out at 0C for 2 hours. After completion of the reaction, the precipitated triethylaniine hydrochloride and 2-mercapto4,6- dimethyl-pyrimidine were filtered off and the filtrate was washed, dried, and recrystallized as well removing the solvent by distillation using the same procedure EXAMPLE l8 Crystals of N-benzyloxycarbonyl-L-alanine 4,-dimethyl-pyrimidine-Z-yl thiolester (0.01 mole) obtained in Example 9 was dissolved in ml of ethyl acetate, and 0.01 mole of glycine ethyl ester hydrochloride and 0.01 mole of triethylamine were added to the resulting solution. The coupling reaction was carried out at 0C for 2 hours. After completion of the reaction, the precipitate was filtered off and the filtrate was washed, dried, and recrystallized as well as removing the solvent by distillation using the same procedure as described in Example 14. The obtained crystals have a melting point of l00l01C and the data of elementary analysis were agreed to those of Z-L-Ala-Gly-OEt. The yield thereof was 94 percent.

Table 7 N-proteeted amino Amino acid or Run N-proteeted acid 4.6-dimethyl peptide ester Peptide Yield M.P. Specific No. amino acid pyrimidine-Z11 (hydrochloride) (7! ("C) rotation thiolester lalf CHI! 26.5 1 Z-L-Val-OH Z-L-Val-S- I L-Phe-OEt 7.-L-Val-l.-Phe()Et 9] I39 (C=l. EtOH) 2 Z-L-Ala-OH ily-Ol-lt /.-l .-Ala-(ily-()lit 95 EXAMPLE l9 N-benzyloxycarhonyl-glycinc 4,6-dimethylpyrimidine-Z-yl thiolester was synthesized using the same process as described in Example 6 except that 0005 mole of 2-mercapto-4.6dimethyl-pyrimidinc and 15 ml of dioxane were used instead of 0.01 mole of 2-mereaptopyrimidine and 50 ml of ethyl acetate. To the obtained reaction solution, 0.99 g (0.006 mole) of L- phenylalanine dissolved in 12 ml of a 0.5 N aqueous solution of sodium hydroxide (L-PheONa) was added and reacted at 20C for 6 hours. After completion of the reaction, the dioxane was removed by distillation. To the residue, l0 ml of water was added and the re sulting solution was washed with ethyl acetate. After 50 adjusting the solution to pH 2 with a 2 N aqueous solution of hydrochloric acid, the resulting solution was extracted with ethyl acetate. The extract was dried over magnesium sulfate and then the solvent was removed by distillation to obtain L44 g of Z-Gly-L-Phe-OH; 55

ysi (Ii (5 wherein R, and R are individually hydrogen or methyl; R is C alkyl which may contain one or more halogens or hydroxyls, C alkenyll, phenyl which may contain hydroxyl, nitro, amino, or methyl, naphthyl, anthryl, 5- or 6-membered heterocyclic ring which may contain one or more hetero atoms of O, N or S, phenyl- C alkyl which may contain methoxy, halogen, nitro or C alkyl on the benzene mueleus, phenyl-C alkenyl, a group of the formula CHNH*A wherein R is a substituent .at the a-earbon of an ,B-amino acid and A is hydrogen or a protective group for an amino acid,

wherein R, is hydrogen or hydroxyl and A is as defined above. -CH CH NH.A wherein A is as defined above, 

1. A PYRIMIDINE DERIVATIVE REPRESENTS BY THE FORMULA,
 2. A pyrimidine derivative according to claim 1, where R3 is C1-5 alkyl or C2-5 alkenyl.
 3. A pyrimidine derivative according to claim 1, wherein R3 is phenyl, hydroxyphenyl, nitrophenyl, aminophenyl, dimethylaminophenyl, tolyl, naphtyl, anthryl, furyl or pyridyl.
 4. A pyrimidine derivative according to claim 1, wherein R3 is phenyl-C1-5 alkyl or cinnamic.
 5. A pyrimidine derivative represented by the formula,
 6. A pyrimidine derivative according to claim 1, wherein R3 is a group of the formula,
 7. A pyrimidine derivative according to claim 1, wherein A is benzyloxycarbonyl, p-methoxybenzyloxycarbonyl, tert-butyroxycarbonyl, tert-amyloxycarbonyl, phthaloy, or benzhydryloxycarbonyl.
 8. A pyrimidine derivative of the formula,
 9. A pyrimidine derivative of the formula,
 10. A pyrimidine derivatice of the formula,
 11. A pyrimidine derivative of the formula,
 12. Acetyl pyrimidine-2-yl thiolester, or acetyl 4-methyl or 4, 6-dimethyl-pyrimidine-2-yl thiolester.
 13. Benzoyl pyrimidine-2-yl thiolester or benzoyl 4-methyl or 4, 6-dimethyl-pyrimidine-2-yl thiolester.
 14. Cinnamoyl pyrimidine-2-yl thiolester, or cinnamoyl 4-methyl or 4,6-dimethyl-pyrimidine-2-yl thiolester.
 15. N-benzyloxycarbonyl-glycine pyrimidine-2-yl thiolester, or N-benzyloxycarbonyl-glycine 4-methyl or 4,6-dimethyl-pyrimidine-2-yl thiolester.
 16. N-benzyloxycarbonyl-phenylalanine pyrimidine-2-yl thiolester, or N-benzyloxycarbonyl-phenylalanine 4-methyl or 4,6-dimethyl-pyrimidine-2-yl thiolester.
 17. N-benzyloxycarbonyl-leucine pyrimidine-2-yl thiolester, or N-benzyloxycarbonyl-leucine 4-methyl or 4,6-dimethyl-pyrimidine-2-yl thiolester.
 18. N-phthaloyl-glycine pyrimidine-2-yl thiolester, or N-phthaloyl-glycine 4-methyl or 4,6-dimethyl-pyridine-2-yl thiolester.
 19. N-benzyloxycarbonyl-valine pyrimidine-2-yl thiolester, or N-benzyloxycarbonyl-valine 4-methyl or 4,6-dimethyl-pyrimidine-2-yl thiolester.
 20. N-benzyloxycarbonyl-proline pyrimidine-2-yl thiolester, or N-benzyloxycarbonyl-proline 4-methyl or 4,6-dimethyl-pyrimidine-2-yl thiolester. 